Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
1992.08.28
73-02-00
Page 11
Export Control Classification: PL/UE 9E999
When the main rotor collective pitch lever will be set in the position corresponding to the smallest blade pitch of the main rotor,
the CL shifting from the position Gl to the position > 90° (e.g. 90 100°) causes the . setting of the FLIGHT IDLE (Fl) rating and
switching to the AUTOMATIC OPERATION mode.
D.
Steady state rating.
In the automatic control mode, the electronic limiter unit produces the electric signal controlling the operation of the
electrohydraulic servo valve, which is situated in the bypass line. The flow orifice of the electrohydraulic servo valve slide pair is
the smallest orifice in the bypass line and determines the controlling fuel capacity. Thereby together with the comparative valve
and release valve it controls the metered fuel capacity delivered to the engine combustion chamber. The engine operation
rating is automatically set as, so the available engine power will be equal to the required power of the main and tail rotors at the
constant power turbine rotational speed maintained by the electronic limiter unit.
The pilot has a possibility to correct the setting of the power turbine rotational speed maintained by the electronic limiter unit.
In the EMERGENCY OPERATION mode, the electronic limiter unit is detached, the electrohydraulic servo valve is fully
opened and blocked. The controlling fuel capacity in the bypass line is controlled by the power turbine rotational speed limiter.
Its setting is lowered and it acts as the governor of the power turbine rotational speed. It maintains the constant power turbine
rotational speed in accordance to its characteristic, automatically setting such engine power rating, that the available power will
be equal to the required power of the main and tail rotors. '
If the CL is set to the position α
CL
< 90°, than it limits the available engine power through the fuel capacity limitation passed to
the engine through the throttle valve.
In the manual control mode, at the power turbine rotational speed setting smaller than the electronic limiter unit setting, the
governor determining the controlling fuel capacity is the pressure drop valve. With the increase of the throttle valve flow orifice,
kinematically connected to the CL, and moving to the higher engine operation ratings, in the moment when the power turbine
rotational speed will be equal to the setting of the electronic limiter unit, the control is taken over by the electronic limiter unit.
E.
Deceleration.
The decrease of the main rotor blade pitch by the collective pitch lever causes the power turbine rotational speed increase and
immediate creation of controlling signal by the electronic limiter unit, causing the decrease of the fuel capacity in the controlling
fuel main - the slide pair flow orifice of the electrohydraulic servo valve will be closed. The bypass main and the governors
contained in it will be disengaged of the operation.
